Gas mask breathing resistance



2 Sheets-Sheet 1 Filed March 31, 1958 INVENTOR. Armard llMafsin ATTORNEYA. ,V. MOTSINGER GAS MASK BREATHING RESISTANCE Oct. 13, .1959

Filed Match 51, 1958 2 Sheets-Sheet 2 l/VVE/VT'OR Armard V. Mats/rigorBY A WM AT TORNE) 2,908,272 GAS MASK BREATHING RESISTANCE Armard V.Motsinger, Aberdeen, Md. Application'March 31, 1958, Serial No. 725,457

8 Claims. (Cl. 128-141) Granted under Title 35, U.S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment to me of any royalty thereon.

This invention relates to a face mask, and more particularly relates toa meansfor both reducing breathing resistance and for continuousdefogging of the eyelens of a face mask.

It has long been a problem in the face mask art to devise means toreduce breathing resistance in conventional masks in order that thewearer may more comfortably wear a mask for a longer time. It is wellknown to anyone who has ever worn a conventional gas mask that breathingis somewhat diflicult, particularly deep breathing. Upon undergoingphysical activity that requires faster and deeper breathing, thepresently known masks do not allow the proper flow of air to assure thecomfort of the wearer. This has resulted either in a tendency to removethe mask sooner than it is deemed proper or in necessarily reducedactivity. An obvious solution has been to increase the canister size andweight, but this has serious disadvantages'in that such increases wouldnaturally impede the activities of the wearer.

A further problem, fogging of the lenses, has plagued the art,particularly in cold climates. However, substantial advances have beenmade in overcoming this problem by directing incoming airfrom thecanister over the inside of the lenses of the face piece. While thisstructure has met with limited success, it has been found thatfrequently the lenses have fogged during exhalation particularly astemperature conditions become more severe.

The shortcoming of the old masks has been that the air used fordefogging enters only during the inhaling cycle of breathing, whileduring exhalation no air is drawn across the lenses. It is during thislatter period that fogging has been experienced, particularly due to theescape of minute amounts of exhaled breath from'about the nose pieceinto the area surrounding the eyelenses. Regardless what amount of airis drawn across the eyelenses, if it is not continuous, it has beenfound that some fogging will occur during exhalation. In prior artmasks, it is not possible to have a continuous flow of air across theeyelenses.

Thus, it is an object of this invention to provide a face'mask thatreduces breathing resistance.

Another object of this invention is to prevent fogging of lenses undervarying climatic conditions.

Another object is to continuously defog the eyelenses throughout thebreathing cycle.

Another and more specific object is to reduce the size and weight of thecanister and not increase the breathing resistance of the wearer.

Another object is to produce a longer period of effectiveness forconventional canisters.

Other and more specific objects, as well as-a clear understanding of theinvention, will be had upon reference to the drawing and the includeddetailed description.

Patented Oct. 13, 1959 'mcommunication with both'the canister andinterior of the mask, will provide an additional supply of air whichmaybe drawn from upon inhalation to ease breathing. This surge chamber,after deflating due to inhalation, will expand due to its inherentresiliency and draw air into the mask from the canister even while thewearer is exhaling. This novel feature provides a continuous stream ofair which is directed onto the eyelensesof'the mask so as to preventfogging.

In the drawing:

Fig. 1 is a view of the complete mask assembly.

Fig. 2 is an enlarged sectional View of mask showing Figs. 3, 5 and 7are sectionalviews of modified forms of surge chambers.

Figsq4, 6 and 8 are perspective views of the modifications of Figsj3, 5and 7, respectively.

Referring to'the drawing, 10 indicates a facepiece, having a faceblank11 with the usual harness assembly (not shown), while generally at 12 isshown a conventional eye piece consisting of eyelenses 14 and 15, andeyerings 16 and 17. While I have shown two lenses, it will be understoodthat a single lens extending the width of the facepiece may be employed.Inside the mask is the usual nose cup'18 and nose cup oneway inletvalves 20 and 21 respectively, the nose cup being designed to fitsecurely around the nose of the wearer to control the entry and exit ofair in a well known manner. At 22 is shown a conventional outlet valvecomprising the usual cover, disk and seat (the latter two not shown). Topurify theincoming air a canister 24, which is of conventional designhaving a particulate filter and gas absorbant material, is secured tothe canister mounting piece 26. A flexible disk 28 functioning as a oneway valve is secured to the underside of the canister mounting piece 26by a snap fastener 30. All the foregoing structure is not asserted to benovel, but rather is a part of well known masks used in recent years.

The canister mounting piece 26 is secured to the outside wall 32 of theface blank. This wall forms with inside wall 34 a canister air pocket 36which extends only over approximately one-half of the front portion ofthe face blank and is in air communication with the canister. Directlyunder the eyelens 14 is the sole outlet 38 for the canister air pocketproviding communication between the canister and the interior of theface blank 11. On the opposite side from the canister is a substantialduplicate of the double walled canister air pocket forming the surgechamber air pocket 46 with its outer and inner walls 42 and 44 and anoutlet 48 providing communication between the surgechamber and theinterior ofthe face blank. The two pockets 36 and 46 are not in fluidcommunication except through their respective outlets 38 and 48. Theoutlet 48 in the surge chamber air pocket is similarly situated inrelation to lens 15 as outlet 38 is to lens 14. Secured to the outerwall 42 is a tube 50 providing air communication between the surgechamber 52 and the pocket 46, the tube 50 and the surge chamber beingconnected by a ferrule 54 in a conventional manner. The surge chamber 52may be made of any flexible, elastic air tight material such as rubberor synthetic plastic with a resiliency sufficient to deflate uponinhalation and to expand to its normal size after inhalation. Theconfiguration is not critical, but for convenience and ease of wearing,the shape of the preferred embodiment is in the form of sections asshown, each in communication with the other. The surge chamber may bemade with a uniform resiliency throughout its length, or as amodification, it may be made less yielding in certain portions which maybe accomplished, for example, by using a greater thickness of materialat the less resilient portions. The purpose of this modification is toprovide a reserve volume to be used only upon the deepest breathingwhile during normal breathing only the more resilient portions areoperating, or also to insure an equal deflation in all sections at thesame time. A snap fastener 56 is provided to secure the end of the surgechamber around the neck of the wearer onto the other side of the mask.The surge chamber thereby also functions as a neck strap to moresecurely hold the face piece to the face.

In operation, the fresh air flows during inhalation, as indicated by thesolid arrows, through the canister into the canister air pocket 36through the outlet 38 onto the lens 14 and then into one or both of thenose cup valves. At the same time, air is drawn from the surge chamber52 into pocket 46 and then through outlet 48 onto lens 15 and also intoone or both of the nose cup valves. Air is thus directed onto bothlenses and into the eyelens compartment formed by the nose cup, theeyelens, the facepiece and the wearer from which it is breathed by thewearer through the one way nose cup valves 20 and 21. This novel featureof using a surge chamber has resulted in a reduction in breathingresistance as shown by the following test made with a conventionalbreathing machine having a pulsating flow simulating actual breathing, asurge chamber of 430 ml. capacity and a standard US. Army M11 activatedcharcoal type canister having continuous flow resistance of 68 mm. H Oat 85 l./m. Normal breathing is at the rate of about -15 l./m.

Effect of surge chamber of breathing resistance Pulsating to simulateactual breathing.

It is clear that a larger surge chamber would provide an even greaterreduction in breathing resistance, especially at higher breathing ratesdue to increased work loads.

Upon exhalation, the novel features of this'invention are further inevidence. In conventional masks, air is not continuously drawn acrossthe lenses whereby fogging usually occurs during exhalation. But as isclearly shown in Fig. 2, the dotted lines indicate that there is a flowof fresh air during the exhaling cycle of breathing and that it is drawninto the canister through the eyelens compartment and across the lenses1-4 and into the deflated (by inhalation) surge chamber to expand thesame. The surge chamber acts automatically in this operation to defogthe lenses during exhalation or after inhalation without any assistancefrom the wearer except his breathing. Further, it should be evident thatthere is a continuous flow of air into the mask which is continuouslydirected onto the lenses for defogging in a manner wholly different thanheretofore known in the prior art.

A further advantage of this continuous flow of air through the canisteris that for a given depth of absorbent in a canistcrto which canisterweight is proportional the canister is capable ofperformingsatisfactorily for a greater total volume of air or effectivegas protection life when there. is a continuous flow than when there isa strong pulsating air flow. The reason for this is a simple one, thefaster the air flows the less efficient the absorbent, and thus for fastpulsating flowing air which is necessary to obtain the required volumeper unit time, a deeper and therefore a heavier canister is required. It

also should be noted that if the same total volume of air per unit timewere required by the wearer, the canister size necessary would be ableto be reduced if there were continuous flow than if there were apulsating flow.

The position of the surge chamber and its outlet 48 in relation to thecanister is preferably such as shown in the drawing. Thisrelationshippermits air to be drawn across the lenses for defogging duringexhalation, whereas if the surge chamber and outlet were between thecanister and the mask there would be no such function during exhalation.In the latter position, the instant surge chamber would act to reduceresistance, but not reduce fogging and thus would not perform thefunctions of the invention.

While there has been described above one complete embodiment of the maskemploying one particular form of surge chamber, there are various otherdesigns that are usable and which may be preferred in some instances.Thus, in Figs. 3-6 are shown two types of surge chambers that need notbe made of resilient material but rely upon springs for operation. Themodification of Figs. 3 and 4 is a bellows formed of two rigid plates60, 62 of light metal plastic or the like joined by hinge 64 and anaccordion-pleated bag 66 which may be made of any suitable impermeablematerial. Plate 60 carries an inlet tube 68, which is secured to thetube 50 of the mask at the same point as the surge chamber 52 as shownclearly in Figs. 1 and 2. Plate 60 may lie directly against thefacepiece of the mask. Within the chamber formed by plates 60 and 62 isa bifurcated spring 70 which seats on ledges 72 of plates 60, 62. Thisspring tends to force plates 60, 62 apart and will be of a strength suchthat it will compress and expand according to the breathing cycle. Bag66 need not be elastic in this case.

Another alternate type of bellows making use of a spring is shown inFigs. 5 and 6. This embodiment comprises a flexible spirally pleated bag74' which surrounds a suitable spiral spring 76. The bag is providedwith an inlet tube 78. Again, the spring tends to expand the bellows butis compressed upon inhalation.

The chambers of Figs. 3-6 have certain advantages over that of Figs. 1and 2. Since these embodiments use springs, which can be more accuratelydesigned than rubber chambers, their expansive action can be morereadily controlled. Further, as they are supported on the side of theface piece opposite the conister, they provide a balancing of the weighton the face piece. Moreover, the elasticity of the springs does notchange on storage as does that of rubber. On the other hand, they aremore complicated in structure and, due to their position, may providemore interference in the use of a weapon or instrument.

A further embodiment of the chamber is shown in Figs. 7 and 8. Like themodification of Figs. 1 and 2, it is made of resilient rubber and passesaround the back of the wearers neck. It is, however, different in form,comprising a plurality of longitudinal pleats which expand radially.This form oifers somewhat less resistance to air flow at high breathingrates than the modifications of Figs. 1 and 2, and for a givenresiliency can be made of somewhat heavier and therefore sturdiermaterial.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentinvention that come within the province of those skilled in the art;however, it is intended that all such variations in structure, modes ofusage and materials be considered to be within the scope of thisinvention as limited solely by the appended claims.

I claim:

1. A gas mask comprising a facepiece, having an outside wall, an airinlet means on said outside wall on a first side of said facepiece, atleast one transparent lens member on said facepiece, an air outlet meansmounted jacent a lens member, a second air pocket and an outlet for saidsecond air pocket adjacent a lens member, and an expansible surgechamber in open communication with said second air pocket, whereby whenthe wearer inhales, air will be drawn through said air inlet means andfrom said surge chamber across a lens member and into said nosecup,while when the wearer exhales said surge chamber will expand and drawair through said air inlet across a lens and into said surge chamber.

2. The structure of claim 1 wherein the surge chamber is flexible andelastic.

3. The structure of claim 1 wherein the surge chamber is expanded bybiasing means.

4. The structure of claim 1 wherein the surge chamber is hinged at oneend and expandable at an opposite end by a bifurcated spring.

5. The structure of claim 3 wherein the surge chamber is expanded by acoil spring.

6. The structure of claim 1 wherein the surge chamber is pleated elasticand radially expandable.

7. The structure of claim 1 wherein the surge chamber is elongated andconstructed of a more resilient material at one portionof its lengththan at a second portion of its length whereby the expansion of thesurge chamber is controlled throughout its length.

8. A device as defined in claim 1 wherein said surge chamber iselongated and resilient, said chamber having an open end connected tosaid second air pocket and being closed at its other end, cooperatingdetachable fasteners on said facepiece and on the closed end of saidsurge chamber, the fastener on the facepiece being positioned on theside opposite said second air pocket, and the surge chamber beingsufliciently long to fit around the back of the wearers neck.

References Cited in the file of this patent UNITED STATES PATENTS2,077,054 OLeary Apr. 19, 1937 2,365,779 Schwab Dec. 26, 1944 2,810,386Reed Oct. 22, 1957

